This patent application claims priority to U.S. Provisional Patent Application Serial No. 60/259,455, filed on Jan. 3, 2001. This application relates to a swivel wheel assembly with adjustable shock absorption. The invention is especially applicable for use on utility vehicles, such as trailers, adapted for being hauled. The invention is easy to maneuver, and includes an adjustable shock absorber which allows custom stabilization of the vehicle for a smoother ride when towed. In a preferred embodiment, the utility vehicle has a conventional bumper pull and two identical laterally-spaced swivel wheel assemblies.
Swivel wheel assemblies for utility vehicles are well known in the prior art. According to one such assembly described in U.S. Pat. No. 4,372,569, a vehicle wheel is rotatably mounted on a wheel axle beneath a shock absorber. A pair of wheel support arms are connected at one end to the wheel axis and at the opposite end to a pivot pin located between two compression springs of the shock absorber. The shock absorber is connected to a swivel plate which allows swivel movement of the wheel assembly about a vertical axis. In this assembly, the degree of shock or energy absorption is dictated by a predetermined biasing force created by the compression springs. Because the spring compression is not adjustable, the resulting energy absorption cannot be custom set based on the particular load being carried on the vehicle.
The present invention overcomes this and other problems of prior art swivel wheel assemblies by incorporating a shock absorber which is highly efficient and conveniently adjusted to accommodate the exact load being hauled. Custom adjustment of the shock absorber provides a smoother ride and better handling of the vehicle when towed. In addition, the invention is relatively easy to assemble and disassemble.
Therefore, it is an object of the invention to provide swivel wheel assembly for use on a utility trailer to facilitate maneuverability of the trailer.
It is another object of the invention to provide swivel wheel assembly incorporating a shock absorber which is readily adjustable to accommodate the particular load being hauled.
It is another object of the invention to provide swivel wheel assembly incorporating a shock absorber which is highly efficient to provide a smooth ride and enhance vehicle handling.
It is another object of the invention to provide swivel wheel assembly incorporating a shock absorber which creates a biasing force acting directly on the pivot member of the wheel assembly.
It is another object of the invention to provide swivel wheel assembly which incorporates multiple shock-absorbing components.
It is another object of the invention to provide swivel wheel which can be quickly assembled and disassembled.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a swivel wheel assembly. The wheel assembly includes a wheel axle. A vehicle wheel is rotatably mounted on the wheel axle. A shock-absorbing wheel fork is secured to opposite ends of the wheel axle. The wheel fork includes first and second elongated spaced-apart support arms located on opposite sides of the vehicle wheel. The support arms have respective distal and proximal ends. The distal ends define respective axle openings receiving the wheel axle. The proximal ends extend beyond a periphery of the vehicle wheel and define respective pin openings. A pivot pin extends through the pin openings formed with proximal ends of the first and second support arms. A base is carried by the pivot pin, and is adapted for pivoting movement about an axis defined by the pivot pin. A vertical swivel shaft is mounted on the base, and is adapted for connecting to an underframe of a vehicle to provide swivel movement of the vehicle wheel about an axis defined by the swivel shaft. A shock absorber is connected to the base for dampening pivoting movement of the base relative to the vehicle wheel, thereby absorbing the energy of sudden shocks to the vehicle wheel during use. Means are provided for adjusting the shock absorber to a selected degree of energy absorption.
According to another preferred embodiment of the invention, the base includes an upper pivoting shock plate having a center web and opposing upwardly turned flanges.
According to another preferred embodiment of the invention, a lower fixed shock plate is located below the upper pivoting shock plate. The lower fixed shock plate is attached to the first and second support arms.
According to another preferred embodiment of the invention, the lower fixed shock plate includes a center web and opposing downwardly turned flanges.
According to another preferred embodiment of the invention, the shock absorber includes a rubber disc located between the upper and lower shock plates.
According to another preferred embodiment of the invention, an elongated retainer bolt extends through respective aligned openings in the upper and lower shock plates and the rubber disc.
According to another preferred embodiment of the invention, the shock absorber further includes a compression spring coiled around the retainer bolt. The spring bears against an underside of the lower fixed shock plate and cooperates with the retainer bolt to urge the upper pivoting shock plate into contact with the rubber disc against a biasing force of the spring.
According to another preferred embodiment of the invention, opposing upper and lower spring caps are located at opposite ends of the compression spring, and have respective aligned openings for receiving the retainer bolt.
According to another preferred embodiment of the invention, the retainer bolt has an external screw thread which receives a complementary-threaded fastener. The fastener cooperates with the spring caps to adjust the compression of the spring and the resulting biasing force acting against the upper pivoting shock plate.
According to another preferred embodiment of the invention, an alignment sleeve is carried on the retainer bolt and extends through the opening formed in the lower spring cap to align the lower spring cap relative to the compression spring.
According to another preferred embodiment of the invention, the wheel axle is an axle bolt having an enlarged head and an external screw thread.
According to another preferred embodiment of the invention, an internally-threaded fastener is applied to the threaded end of the axle bolt to retain the axle bolt in position through the axle openings of the support arms.
According to another preferred embodiment of the invention, the fastener is a castellated nut with slots adapted for receiving a safety pin extending through the axle bolt to further retain the axle bolt in position through the axle openings of the support arms.
According to another preferred embodiment of the invention, the pivot pin is a pivot bolt having an enlarged head and an external screw thread.
According to another preferred embodiment of the invention, an internally-threaded fastener retains the pivot bolt in position through the pin openings of the support arms.
According to another preferred embodiment of the invention, the fastener is a castellated nut with slots adapted for receiving a safety pin extending through the pivot bolt to further retain the pivot bolt in position through the pin openings of the support arms.
In another embodiment, the invention is a shock-absorbing wheel fork for being secured to a wheel axle of a vehicle wheel. The wheel fork includes first and second elongated spaced-apart support arms for being located on opposite sides of the vehicle wheel and having respective distal and proximal ends. The distal ends define respective axle openings for receiving the wheel axle. The proximal ends are adapted for extending beyond a periphery of the vehicle wheel. The proximal ends define respective pin openings. A pivot pin extends through the pin openings formed with proximal ends of the first and second support arms. A base is carried by the pivot pin and is adapted for pivoting movement about an axis defined by the pivot pin. A vertical swivel shaft is mounted on the base, and is adapted for connecting to a frame of a vehicle to provide swivel movement of the vehicle wheel about an axis defined by the swivel shaft. A shock absorber is operatively connected to the base for dampening pivoting movement of the base relative to the vehicle wheel, thereby absorbing the energy of sudden shocks to the vehicle wheel during use. Means are provided for adjusting the shock absorber to a selected degree of energy absorption.